Method of making inner tubes



Patented Aug. 3I, 1926., i

UNITED STATES PATENT- OFFICE.

ERNEST W. MELVIN, OF MILWAUKEE, WISCONSIN,

COMPANY, OF CHIGOPEE ASSIGNOB TO THE FISK RUBBER SETTS- METHOD OF MAKING INNER TUBES. Ho Drawing. Application filed December 17, 1924. Serial No. 756521.

My invention relates to the manufacture of inner tubes for pneumatic tires and more particularly to the treatment of such tubes during vulcanization.

. According to one conventional method the raw tube is formed by forcing warm plastic rubber through a circular die of a tubing machine. The tubed stock is then cut into lengths as desired,. positioned on a cylindrical mandrel, and wrapped with strips of fabric. The purpose of the wrapping is to hold the raw stock in close contact with the mandrel and prevent the entrance of steam between the tube and mandrel during vulcanization.

It is among the objects of my invention with the necessity of wrapping ing operation. b

In carrying out my improved method I tube. the stock and position the raw tube on the mandrel in any conventional or desired manner" except that theraw tube is slightly longer. I then turn the ends of the tube back for about an inch'. The turned back portions of the tube exert sufficient tension to .efiectively seal the ends of the raw tube against the mandrel, preventing the entrance of steam between the tube and mandrel without the necessity of any wrapping. The vulcanization may be carried out in any conventional manner.

1. The method of making inner tubes for pneumatic tires which comprises forming the raw tube with a length in excess of normal requirements, positioning theraw tube on a mandrel, the ends of the raw tubebeing turned baclqand subjecting the tube to vulcanization.

'2. The method of making inner tubes for pneumatic tires which comprises tubing the stock 'to a length in excess of normal require FALLS, MASSACHUSETTS, A CORPORATION OF MASSACHU- ments, positioning the raw tube on a mandrel, turning back the ends of the tube, and subjecting thetube to vulcanization.

3. The method of making inner tubes for pneumatic tires which comprises tubing the stock to a length in excess of normal requirements, positioning the raw tube on a cylindrical mandrel, turning back the ends of the tube for a distance of substantially an inch, and subjecting the tube to vulcanization.

In testimony whereof I have signed my name to the above specification.

ERNEST W. MELVIN. 

